A. Field of the Invention
This invention relates to novel singles yarn and its production, and is more particularly concerned with improved singles yarn for use as pile in pile fabrics, especially cut pile carpets.
B. Description of the Prior Art
Over 500 million square yards or 418 million square meters of cut pile carpeting are now being produced annually most of which is produced from nylon. With present technology to achieve cut pile with acceptable aesthetics requires a torque balanced two-ply heatset yarn. However, it would be highly desirable to use a twisted heatset singles yarn since it is usually less expensive to produce a large denier singles yarn rather than the two yarns required to form a plied yarn of the same denier. Also, it is cheaper to twist a singles yarn than to form a plied yarn. Additionally, to have both a singles and plied yarn would offer fabric designers more flexibility. Unfortunately, unless a singles yarn is highly twisted, cut pile prepared therefrom lacks tuft rigidity (i.e. the tufts lack bending resistance and column strength) and consequently will not stand up. Also, the cut pile lacks end point definition because the tufts tend to expand, balloon and untwist until they become snarled with neighboring tufts, giving the pile a matted appearance wherein the individual tufts become undistinguishable. On the other hand, highly twisted singles yarns are torque lively thereby causing difficulties in commercial heatsetting processes. Moreover, the torque liveliness of the highly twisted singles yarn is not removed by commercial heatsetting processes and, therefore, the yarn must be processed at high tensions to avoid kinks which would obstruct delivery tubes and needles of tufting machines. And, even if the highly twisted, torque lively, singles yarn were processed into cut pile, the resulting tufts would tend to be non-uniform, lack bulk, untwist and generally provide a cut pile having poor aesthetics.
U.S. Pat. No. 3,968,638 describes a singles yarn for cut pile consisting of a highly entangled, textured singles yarn to which a latent false twist has been imparted. The latent crimp and twist are developed by heat and moisture after tufting such as in the dyeing or finishing operations. However, cut pile produced from this yarn lacks desired aesthetic characteristics of plied heatest yarn, and therefore, has not enjoyed commercial success.
Presently, singles carpet yarns are used to produce level loop pile for commercial applications where durability and low cost rather than aesthetics are of primary importance. Singles yarn used in level loop pile is not twisted and therefore is also not heatset, thereby saving the cost of these yarn processing operations. However, for some commercial carpeting applications, such as libraries, offices, etc., it would be highly desirable to provide an attractive cut pile at a price competitive with level loop pile carpeting.